At this season, it seems apt to quote the American humourist, P. J. O’Rourke:

“I have only one firm belief about the American political system, and that is this: God is a Republican and Santa Claus is a Democrat.

God is an elderly or, at any rate, middle aged male, a stern fellow, patriarchal rather than paternal and a great believer in rules and regulations. He holds men accountable for their actions. He has little apparent concern for the material well being of the disadvantaged. He is politically connected, socially powerful and holds the mortgage on literally everything in the world. God is difficult. God is unsentimental. It is very hard to get into God’s heavenly country club.

Santa Claus is another matter. He’s cute. He’s nonthreatening. He’s always cheerful. And he loves animals. He may know who’s been naughty and who’s been nice, but he never does anything about it. He gives everyone everything they want without the thought of quid pro quo. He works hard for charities, and he’s famously generous to the poor. Santa Claus is preferable to God in every way but one: There is no such thing as Santa Claus.”

This asymmetry works to the Left’s advantage. It’s human nature to overlook the failings of a politician, party or institution if its motives are visibly benign. The United Nations has been involved in all manner of scandal, from ivory smuggling to running prostitution rings, but it embodies the lofty ideal of brotherhood among nations: it means well. The EU is corrupt, undemocratic and wasteful, but it was established to guarantee peace in Europe: it means well. Every Labour government, without exception, has increased unemployment, but Labour politicians care about the poor: they mean well.

To put it another way, our generation elevates the moralistic (holding the right opinions) over the moral (doing the right thing). You can fiddle your taxes, betray your wife, mistreat your pet, but nothing – nothing – is as shocking as to voice the wrong views about, say, race relations.

Spend five minutes in an online discussion and you’ll see how easily Lefties use the word “evil”, in the sense of “evil Tory scum”. What’s most striking is not the rudeness but the narcissism. It’s as if, having dispensed with the religious notion of wickedness, Lefties have redefined “evil” to mean “someone who disagrees with me”.

Not all, Lefties, obviously. I have Labour-voting friends who are motivated by a more or less uncomplicated desire to help the disadvantaged. But louder, by far, is what we might call the Lily Allen Tendency:

“You sayIt’s not okay to be gay,Well I think you’re just evil.You’re just some racist who can’t tie my lacesYour point of view is mediaeval.”

Evil? Look, I supported civil partnerships long before most Conservatives; I even opposed Section 28 at the time, rather than in retrospect. But were the people who disagreed with me all evil? Even Mother Theresa?

It isn’t just angry teens who think this way. You get it from Labour MPs, Guardian columnists and the like. Count how many people on Twitter cheerfully proclaim in their bios that they “hate” Tories, “hate” Republicans, “hate” neo-liberalism. Sure, you’ll find one or two “hates socialism”, but it’s far, far rarer. Having defined politics, in your own mind at any rate, as a battle between good and evil, you can enjoy hating the other side. “Let’s all get together and have a good hate,” said George Orwell, satirising his fellow-socialists. If you’re self-righteous enough, you might even be able to aver without irony that we should “refuse to tolerate intolerance”, “not listen to such prejudiced people”, “hate the haters”, “refuse to read that bigoted rag”. Lily again:

“F**k you!F**k you very, very much!‘Cause we hate what you doAnd we hate your whole crew,So please don’t stay in touch.”

To repeat, there are Lefties who rise above it. Nick Cohen recalled his shock, as a fourteen-year-old, at discovering that his teacher, an eminently decent man, voted Conservative. In his case, it led him to reconsider his view of Tories. Many others instead reconsider their view of their teacher.

These others, if they’ve read this far, will now be spluttering with rage. How can I possibly say that hatred is a Leftist characteristic when everyone knows that Right-wingers are the worst haters of all? It’s a telling response since a) it proves the point; and b) it’s not true.

Quantitative evidence is hard to come by. We can all cite Twitter. We can all point to Lily Allen Tendencies in supposedly serious commentators (John McTernan and George Monbiot are two people I’ve recently spotted on Twitter claiming that Tories are motivated by some kind of malignity). But where’s the empirical data?

Well, one way to test whether there is a Left-Right difference is to ask people whether they would drop a friend if they found out that the friend voted the other way. And, conveniently enough, precisely such a poll was carried in the New Statesman last month. Labour voters were twice as likely as Tories to find it harder to be friends with someone who voted for the other party, and ten times likelier to be find it easier to be friends with someone who shared their allegiance.

For proper qualitative and quantitative analysis, though, we need to look at the extensive surveys undertaken by the American psychology professor, Jonathan Haidt. Among other things, he asks people to answer a series of political questions as themselves, as a typical Right-winger, and as a typical Left-winger. Rightists, it turns out, have little difficulty imagining themselves as Leftists and answering accordingly; but the reverse is not true.

To find out why this asymmetry exists, you’ll have to read Haidt’s book, The Righteous Mind. I can give only a perfunctory summary here. Essentially, he finds that Left-wingers are motivated by an exaggerated concern for the underdog, the perceived victim, the oppressed group. Right-wingers have that sense, too, but, in their brains, it is balanced by a number of other tendencies: concern for reciprocity, for group loyalty, for sanctity and so on. Because Rightists have the pro-underdog trait, too, they understand well enough what is actuating their opponents. But most Leftists lack the complementary parts of the conservative brain. Their reasoning therefore goes something like this. “I’m a nice person. I care about poor people and ethnic minorities and the oppressed. You’re opposed to me, so you hate them.”

Now we Evil Tory Hatemongers can respond in various ways. We can dismiss our critics, laugh at them, patronise them. Or we can try to show that the free market is the underdog’s truest friend. Almost every tax, almost every regulation, almost every tariff falls on the little guy. Capitalism is the only system yet devised where the masses are truly in charge.

You can hold a conviction against the evidence only for so long. Most of us see through Father Christmas before we’re ten; but we should be gentle with those who take longer.